Hmm, well I do have a lot of Bleach and I'm not particularly interested in the other two series. Meh, I guess you should find out if someone lost them, though I doubt someone would lose that many books or place them in a small bush without some sort of odd reason.
Yeah, I'd probably give them to a friend in that case, granted that you didn't want them. Ah, the price we pay for manga is so high (NZD$20~ per tankobon is a lot to me). I've also run into storage problems, but only because I put my manga and anime collection in a small bookcase in my closet so the light can't destroy it.